Update Xray for PNaCl

native_client_sdk/src/libraries/xray/browser.c

Index: native_client_sdk/src/libraries/xray/browser.c
diff --git a/native_client_sdk/src/libraries/xray/browser.c b/native_client_sdk/src/libraries/xray/browser.c
new file mode 100644
index 0000000000000000000000000000000000000000..bf1062301ccb39067b4aefd7008dc99b5080e8dc
--- /dev/null
+++ b/native_client_sdk/src/libraries/xray/browser.c
@@ -0,0 +1,131 @@
+/* Copyright (c) 2013 The Chromium Authors. All rights reserved.
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+
+
+/* XRay -- a simple profiler for Native Client */
+
+#ifndef XRAY_DISABLE_BROWSER_INTEGRATION
+
+#include <alloca.h>
+#include <assert.h>
+#include <errno.h>
+#include <stdarg.h>
+#include <stdint.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+#include "ppapi/c/dev/ppb_trace_event_dev.h"
+#include "xray/xray_priv.h"
+
+
+#if defined(XRAY)
+static PPB_Trace_Event_Dev* ppb_trace_event_interface = NULL;
+
+static const char* XRayGetName(struct XRaySymbolTable* symbols,
+      struct XRayTraceBufferEntry* e) {
+  uint32_t addr = XRAY_EXTRACT_ADDR(e->depth_addr);
+  struct XRaySymbol* symbol = XRaySymbolTableLookup(symbols, addr);
+  return XRaySymbolGetName(symbol);
+}
+
+struct XRayTimestampPair XRayGenerateTimestampsNow(void) {
+  struct XRayTimestampPair pair;
+  assert(ppb_trace_event_interface);
+
+  XRayGetTSC(&pair.xray);
+  pair.pepper = ppb_trace_event_interface->Now();
+  return pair;
+}
+
+
+void XRayBrowserTraceReport(struct XRayTraceCapture* capture) {
+
+  const void* cat_enabled = ppb_trace_event_interface->GetCategoryEnabled(
+      "xray");
+  struct XRaySymbolTable* symbols = XRayGetSymbolTable(capture);
+
+  int32_t thread_id = XRayGetSavedThreadID(capture);
+
+  int head = XRayFrameGetHead(capture);
+  int frame = XRayFrameGetTail(capture);
+  while(frame != head) {
+
+    struct XRayTimestampPair start_time = XRayFrameGetStartTimestampPair(
+        capture, frame);
+    struct XRayTimestampPair end_time = XRayFrameGetEndTimestampPair(
+        capture, frame);
+
+    double pdiff = (end_time.pepper - start_time.pepper);
+    double odiff = (end_time.xray - start_time.xray);
+    double scale_a = pdiff / odiff;
+    double scale_b = ((double)end_time.pepper) - (scale_a * end_time.xray);
+    printf("Xray timestamp calibration frame %d: %f %f\n",
+        frame, scale_a, scale_b);
+
+
+    int start = XRayFrameGetTraceStartIndex(capture, frame);
+    int end = XRayFrameGetTraceEndIndex(capture, frame);
+    int count = XRayFrameGetTraceCount(capture, frame);
+
+    struct XRayTraceBufferEntry** stack_base = XRayMalloc(
+      sizeof(struct XRayTraceBufferEntry*) * (count + 1));

[nfullagar1, 2013/07/18 21:36:00]

So XRay has a max stack depth that it will capture (XRAY_TRACE_STACK_SIZE). 
When surfing trace data, nothing will be deeper than that.  Also, instead of
comparing timestamps (which in some rare cases might go backwards if thread
jumps from one physical cpu to another and their hw counters aren't in sync.  We
might need to protect against this and fudge the numbers if about:tracing yacks,
but that could be for another CL), you could push/pop to your stack comparing to
the depth field.  In the ascii reporting code, the depth field is simply the
number of spaces to print before printing the function name.

[grosse, 2013/07/18 23:00:06]

Done.

+    struct XRayTraceBufferEntry** stack_top = stack_base;
+    *stack_top = NULL;
+
+    int i;
+    for(i = start; i != end; i = XRayTraceNextEntry(capture, i)) {
+      if (XRayTraceIsAnnotation(capture, i)) {
+        continue;
+      }
+
+      uint64_t current_tick = XRayTraceGetEntry(capture, i)->start_tick;
+      while(*stack_top && current_tick >= (*stack_top)->end_tick) {
+        struct XRayTraceBufferEntry* e = *(stack_top--);
+        ppb_trace_event_interface->AddTraceEventWithThreadIdAndTimestamp(
+            'E', cat_enabled,
+            XRayGetName(symbols, e),
+            0, thread_id,
+            (scale_a * e->end_tick) + scale_b,
+            0, NULL, NULL, NULL, 0
+        );
+      }
+
+      struct XRayTraceBufferEntry* e = XRayTraceGetEntry(capture, i);
+      ppb_trace_event_interface->AddTraceEventWithThreadIdAndTimestamp(
+          'B', cat_enabled,
+          XRayGetName(symbols, e),
+          0, thread_id,
+          (scale_a * e->start_tick) + scale_b,
+          0, NULL, NULL, NULL, 0
+      );
+
+      *(++stack_top) = e;
+    }
+
+    while(*stack_top) {

[nfullagar1, 2013/07/18 21:36:00]

hmm... it feels like this trace traversal and re-stacking could be done with one
fewer while loop.  This while loop looks very similar to the one above within
the for loop.  Is it possible to merge the two into one and make this function
smaller?

+      struct XRayTraceBufferEntry* e = *(stack_top--);
+      ppb_trace_event_interface->AddTraceEventWithThreadIdAndTimestamp(
+          'E', cat_enabled,
+          XRayGetName(symbols, e),
+          0, thread_id,
+          (scale_a * e->end_tick) + scale_b,
+          0, NULL, NULL, NULL, 0
+      );
+    }
+
+    frame = XRayFrameGetNext(capture, frame);
+    XRayFree(stack_base);
+  }
+}
+
+void XRayRegisterBrowserInterface(PPB_GetInterface interface) {
+  ppb_trace_event_interface = (PPB_Trace_Event_Dev*)interface(
+      PPB_TRACE_EVENT_DEV_INTERFACE);
+  assert(ppb_trace_event_interface);
+}
+
+#endif  /* XRAY */
+#endif  /* XRAY_DISABLE_BROWSER_INTEGRATION */